Thermal fusion 3D printer

Abstract

To provide a thermal-melting type three-dimensional printer capable of suppressing molding defects.SOLUTION: There is provided a thermal-melting type three-dimensional printer that comprises an extruder and a pushing mechanism. The extruder includes a hopper, a cylinder and a nozzle. The hopper is configured to be able to supply pellets into the cylinder through a raw material supply port provided in the cylinder. The extruder is configured to melt and knead the pellets supplied into the cylinder to form a molten resin in the cylinder, and to extrude the molten resin through the nozzle to form a strand. The pushing mechanism is configured to push the pellets placed on a placement surface of the hopper into the cylinder through the raw material supply port.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a thermal fusion type three-dimensional printer. [Background technology]

[0002] Patent Document 1 discloses a method for manufacturing a shaped object by melting pellets made of a thermoplastic elastomer using a screw extruder and extruding them from a nozzle to form a strand, and then scanning this strand. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-146988 A Summary of the Invention [Problem to be solved by the invention]

[0004] The pellets are fed into the cylinder of the extruder through a hopper, and if the pellets have sticky surfaces, they may stick together on the hopper, which is called a bridging phenomenon. If a bridging phenomenon occurs, the pellets will not be fed sufficiently into the cylinder, leading to defective molding.

[0005] The present invention has been made in consideration of the above circumstances, and provides a thermal fusion type three-dimensional printer that can suppress modeling defects. [Means for solving the problem]

[0006] According to the present invention, there is provided a three-dimensional printer of a thermal fusion type, comprising an extruder and a pushing mechanism, the extruder comprising a hopper, a cylinder, and a nozzle, the hopper being configured to be able to supply pellets into the cylinder through a raw material supply port provided in the cylinder, the extruder being configured to melt and knead the pellets supplied into the cylinder within the cylinder to form a molten resin, and to extrude the molten resin through the nozzle to form strands, and the pushing mechanism being configured to push pellets placed on the mounting surface of the hopper into the cylinder through the raw material supply port.

[0007] In the three-dimensional printer of the present invention, the pushing mechanism having the above-described configuration pushes the pellets into the cylinder, thereby suppressing defective modeling caused by an insufficient supply of pellets.

[0008] Various embodiments of the present invention will be described below. The embodiments described below can be combined with each other.

[0009] Preferably, in the three-dimensional printer described above, the pushing mechanism includes a rod that contacts the pellet and a driving mechanism that drives the rod, and the rod is driven so that the tip of the rod presses the pellet in the direction of the raw material supply inlet. Preferably, in the three-dimensional printer described above, the rod has a soft portion, and the rod is driven so that the tip of the rod moves toward the raw material supply port while the rod is bent at the soft portion. Preferably, in the three-dimensional printer described above, the drive mechanism is configured to rotate the base of the rod about a rotation axis extending in a non-vertical direction. [Brief description of the drawings]

[0010] [Figure 1]FIG. 1A is a front view (a cross-sectional view of a cylinder 2b) showing a thermal fusion type three-dimensional printer 1 according to an embodiment of the present invention, and FIG. 1B is a right side view of a pressing mechanism 3 in FIG. 1A. [Diagram 2] FIG. 2 shows a state after rod 3a has been lowered from the state shown in FIG. 1, and FIGS. 2A and 2B correspond to FIGS. 1A and 1B, respectively. [Diagram 3] FIG. 3 shows a state after rod 3a has been further lowered from the state shown in FIG. 2, and FIGS. 3A and 3B correspond to FIGS. 1A and 1B, respectively. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present invention will be described. Various features shown in the following embodiments can be combined with each other. Also, each feature can be an invention independently.

[0012] As shown in FIG. 1, a thermal fusion type three-dimensional printer 1 according to an embodiment of the present invention includes an extruder 2 and a pushing mechanism 3.

[0013] <Extruder 2> The extruder 2 includes a hopper 2a, a cylinder 2b, and a nozzle 2c. The hopper 2a is configured to be able to supply pellets 4 into the cylinder 2b through a raw material supply port 2b1 provided in the cylinder 2b. The raw material supply port 2b1 is preferably provided on the side surface of the cylinder 2b. The hopper 2a is preferably attached to the cylinder 2b, and more preferably attached to the side surface of the cylinder 2b.

[0014] The extruder 2 is configured to melt and knead the pellets 4 supplied into the cylinder 2b within the cylinder 2b to form a molten resin 4a, and to extrude the molten resin 4a through a nozzle 2c to form a strand 5. A screw 2d is disposed within the cylinder 2b, and by rotating the screw 2d with a motor 2e, it is possible to melt and knead the pellets 4 to form the molten resin 4a, and to transport the molten resin 4a toward the tip of the cylinder 2b and extrude it through the nozzle 2c.

[0015] The diameter of the screw 2d is, for example, 5 to 80 mm, and preferably 10 to 60 mm. Specifically, the diameter is, for example, 5, 10, 20, 30, 40, 50, 60, 70, or 80 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0016] The strand 5 is linear and has a diameter of, for example, 0.5 to 6.0 mm, preferably 1.0 to 4.0 mm. Specific examples of the diameter are 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, and 6.0 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0017] The pellets 4 are placed on the placement surface 2a1 of the hopper 2a. The placement surface 2a1 preferably has an angle of 0 to 80 degrees, more preferably 15 to 60 degrees, with respect to the horizontal plane. Specifically, this angle is, for example, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80 degrees, and may be within a range between any two of the numerical values ​​exemplified here.

[0018] The width (length in the depth direction in FIG. 1A) and height of the raw material supply port 2b1 are, for example, 1 to 10 cm, preferably 2 to 8 cm, and specifically, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 cm, and may be within a range between any two of the numerical values ​​exemplified here.

[0019] The extruder 2 can be moved three-dimensionally (in the X, Y and Z directions) by a driving mechanism (not shown). A single-layer structure can be formed by two-dimensionally scanning the extruder 2 while discharging the strand 5 from the nozzle 2c, and a desired object can be formed by stacking the single-layer structures.

[0020] <Pushing mechanism 3> The pushing mechanism 3 is configured to push the pellets 4 placed on the placement surface 2a1 of the hopper 2a into the cylinder 2b through the raw material supply port 2b1. The placement surface 2a1 is usually an inclined surface that becomes lower toward the raw material supply port 2b1, and it is expected that the pellets 4 will be supplied into the cylinder 2b by their own weight. However, if the surface of the pellets 4 is sticky, the pellets 4 may stick together on the hopper 2a, which is called a bridge phenomenon. If the bridge phenomenon occurs, the pellets 4 are difficult to supply into the cylinder 2b by their own weight, resulting in insufficient supply of the pellets 4 and leading to defective molding. On the other hand, in this embodiment, the pushing mechanism 3 pushes the pellets 4 into the cylinder 2b, so that even if the surface of the pellets 4 is sticky, the pellets 4 can be sufficiently supplied into the cylinder 2b, and defective molding caused by insufficient supply of the pellets 4 is suppressed.

[0021] In this embodiment, the pushing mechanism 3 includes a rod 3a that contacts the pellets 4 and a driving mechanism 3b that drives the rod 3a. The pushing mechanism 3 is preferably attached to the extruder 2, and more preferably attached to an upper portion of the extruder 2.

[0022] The rod 3a is driven so that the tip 3a1 of the rod 3a presses the pellets 4 in the direction of the raw material supply port 2b1. In order to eliminate the bridge phenomenon of the pellets 4, it is possible to break the bridge of the pellets 4 with a piston moving in the vertical direction. However, in such a configuration, although the bridge is broken, the pellets 4 may stick to other pellets, and the supply shortage of the pellets 4 may not be sufficiently solved. On the other hand, in the pushing mechanism 3 of this embodiment, the tip 3a1 of the rod 3a does not simply move in the vertical direction, but is driven so as to press the pellets 4 in the direction of the raw material supply port 2b1 as shown in Figs. 1 to 3. According to such a configuration, the bridge of the pellets 4 is broken by the pressure of the tip 3a1 and the pellets 4 are moved in the direction of the raw material supply port 2b1, so that the supply of the pellets 4 into the cylinder 2b is promoted compared to the case where the tip 3a1 is moved in the vertical direction.

[0023] The diameter of the tip 3a1 of the rod 3a is, for example, 1 to 20 mm, and preferably 3 to 15 mm. Specifically, the diameter may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, or 30 mm, or may be within a range between any two of the numerical values ​​exemplified here.

[0024] The rod 3a preferably includes a soft portion 3a2. The soft portion 3a2 is a portion that is curved when the rod 3a is pressed against the placement surface 2a1, and is made of a soft material such as rubber. The flexural modulus of the soft portion 3a2 is preferably, for example, 70 to 700 MPa. Specifically, the flexural modulus may be, for example, 70, 80, 90, 100, 250, 400, 550, or 700 MPa, and may be within a range between any two of the numerical values ​​exemplified here. The rod 3a may be made of only the soft portion 3a2, or is preferably made of the soft portion 3a2 and a hard portion 3a3 made of a material having a flexural modulus higher than that of the soft portion 3a2. The hard portion 3a3 is preferably disposed at a position farther away from the tip 3a1 than the soft portion 3a2. In addition, the tip 3a1 is preferably provided on the soft portion 3a2. The flexural modulus can be measured in accordance with JIS K7171.

[0025] The length of the soft portion 3a2 (the length in the longitudinal direction when the soft portion 3a2 is linear) is preferably 2 cm or more, and more preferably 3 cm or more. The length of the soft portion 3a2 is, for example, 2 to 30 cm, specifically, for example, 2, 3, 4, 5, 10, 15, 20, 25, or 30 cm, and may be within a range between any two of the numerical values ​​exemplified here or any one or more. The cross-sectional shape of the soft portion 3a2 may be constant over the entire length, and may be tapered toward the tip 3a1, for example.

[0026] It is preferable that the rod 3a is driven so that the tip 3a1 of the rod 3a moves toward the raw material supply port 2b1 while the rod 3a is bent at the soft portion 3a2. In this configuration, when the base 3a4 of the rod 3a is moved downward, the tip 3a1 of the rod moves toward the raw material supply port 2b1, and when the base 3a4 of the rod 3a is moved upward, the tip 3a1 of the rod moves in a direction away from the raw material supply port 2b1. In other words, the vertical movement of the base 3a4 of the rod 3a is converted into the movement of the tip 3a1 of the rod 3a approaching or moving away from the raw material supply port 2b1.

[0027] As the driving mechanism 3b, any mechanism capable of operating the rod 3a as described above can be adopted, for example, a cylinder mechanism, a rotation mechanism, etc. As the cylinder mechanism, there is a mechanism that moves the base 3a4 of the rod 3a back and forth in the up and down direction. As the rotation mechanism, there is a mechanism that can convert the rotational motion into the up and down reciprocating motion of the base 3a4 of the rod 3a.

[0028] The drive mechanism 3b of this embodiment is a rotation mechanism, and includes a motor 3b1, a motor shaft 3b2, a disk 3b3, and a bracket 3b4.

[0029] The motor shaft 3b2 is driven to rotate by the motor 3b1. The rotation direction of the motor shaft 3b2 is counterclockwise when viewed from the disk 3b3 side, as shown in FIG. 1B, for example. The disk 3b3 is fixed to the motor shaft 3b2, and the bracket 3b4 is fixed to the disk 3b3. The base 3a4 of the rod 3a is fixed to the bracket 3b4. Therefore, as shown in FIGS. 2 and 3, the disk 3b3, the bracket 3b4, and the base 3a4 also rotate with the rotation of the motor shaft 3b2. The direction of the motor shaft 3b2 coincides with the rotation axis of the member that rotates with the rotation of the motor shaft 3b2.

[0030] Since the motor shaft 3b2 faces in a non-vertical direction, its vertical position periodically changes as the base 3a4 rotates. Therefore, by rotating the motor shaft 3b2, the base 3a4 can be moved back and forth in the vertical direction. The angle between the motor shaft 3b2 and the horizontal plane is preferably 45 degrees or less, and more preferably 30 degrees or less. This angle is, for example, 0 to 45 degrees, and specifically, for example, 0, 5, 10, 15, 20, 25, 30, 35, 40, or 45 degrees, and may be within a range between any two of the numerical values ​​exemplified here or less than any of them.

[0031] In addition, as the motor shaft 3b2 rotates, the base 3a4 not only reciprocates up and down, but also reciprocates left and right in Fig. 1B (a direction perpendicular to both the vertical direction and the direction of the rotation axis of the motor shaft 3b2). When the base 3a4 reciprocates left and right, the tip 3a1 and its vicinity also reciprocate left and right, making the bridge more likely to collapse.

[0032] The amplitude of the tip 3a1 in the reciprocating motion (the length between the position closest to the raw material supply port 2b1 and the position farthest from the raw material supply port 2b1) is, for example, 0.5 cm or more, and preferably 1 cm or more. This amplitude is, for example, 0.5 to 10 cm, specifically, for example, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 cm, and may be within a range between any two of the numerical values ​​exemplified here or any one of them.

[0033] During the reciprocating motion, the tip 3a1 may or may not go inward from the outer circumferential surface of the cylinder 2b. When the tip 3a1 is closest to the cylinder 2b, the distance from the tip 3a1 to the outer circumferential surface of the cylinder 2b is preferably 10 cm or less, more preferably 5 cm or less. This distance is, for example, -2 cm to 10 cm, specifically, for example, -2, -1, -0.5, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 cm, and may be within a range between any two of the numerical values ​​exemplified here or less than any one of them. A negative value means the distance that the tip 3a1 goes inward from the outer circumferential surface of the cylinder 2b.

[0034] <Pellet 4> The pellets 4 are not particularly limited, but are preferably made of a thermoplastic elastomer.

[0035] The pellets 4 are in a granular form that can be fed into the extruder 2. The shape of the pellets 4 is not particularly limited, but may be, for example, spherical or spheroidal. If the length of the longest part of the pellets 4 (in the case of a spheroid, the length in the long axis direction) is L and the diameter of the surface perpendicular to the longest part (in the case of a spheroid, the length in the short axis direction) is D, L / D is, for example, 1 to 10, and preferably 1 to 5. L is, for example, 0.5 to 10 mm, and preferably 2 to 8 mm. L / D is, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, and may be within a range between any two of the numerical values ​​exemplified here. L is, for example, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0036] Examples of the thermoplastic elastomer include styrene-based elastomers, olefin-based elastomers, and acrylic elastomers. The thermoplastic elastomer preferably contains a styrene-based elastomer. Since the styrene-based elastomer has high flexibility, the flexibility of the thermoplastic elastomer increases when the thermoplastic elastomer contains a styrene-based elastomer. The proportion of the styrene-based elastomer in the thermoplastic elastomer is preferably 50 to 100% by mass, more preferably 80 to 100% by mass, and specifically, for example, 50, 60, 70, 80, 90, or 100% by mass, and may be within a range between any two of the numerical values ​​exemplified here.

[0037] The styrene-based elastomer is a thermoplastic elastomer having a styrene unit, and examples thereof include one or a blend of two or more selected from styrene-based copolymers (e.g., styrene-ethylene-styrene block copolymer (SES), styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene rubber (SBR)), hydrogenated styrene-based copolymers (e.g., styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-butylene-butadiene-styrene block copolymer (SBBS), hydrogenated styrene-butadiene rubber (HSBR)), etc.

[0038] The Shore A hardness of the thermoplastic elastomer is preferably 0 to 10, and more preferably 0 to 2. The pellets 4 having such physical properties have a sticky surface, and therefore the technical significance of using the three-dimensional printer 1 of the present embodiment to perform modeling is significant. Specifically, the Shore A hardness is, for example, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, and may be within a range between any two of the values ​​exemplified here. When the Shore A hardness is within this range, a modeled object having excellent flexibility is obtained. The Shore A hardness is measured based on JIS K6253.

[0039] The melt flow rate (hereinafter, "MFR") of the thermoplastic elastomer is preferably 10 to 200 g / 10 min, more preferably 60 to 140 g / 10 min. In this case, it is easy to improve the molding accuracy. Specifically, the MFR is, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200 g / 10 min, and may be within a range between any two of the values ​​exemplified here. The MFR is measured in accordance with JIS K-7210 at a measurement temperature of 150° C. and a test load of 2.16 kg.

[0040] The repose angle of the pellet 4 is preferably 35 degrees or more. Since such a pellet 4 is prone to a bridging phenomenon, the technical significance of using the three-dimensional printer 1 of this embodiment to perform modeling is significant. The repose angle is, for example, 35 to 80 degrees, specifically, for example, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 50, 55, 60, 65, 70, 75, and 80 degrees, and may be within a range between any two of the numerical values ​​exemplified here or equal to or greater than any one of them. The repose angle can be measured by the following method. (1) First, the pellets 4 are poured vertically onto a horizontal measuring table (diameter 10.5 cm) to form a pile of pellets 4. The pellets 4 are poured until they overflow the measuring table. (2) Next, the angle of inclination of the pile of pellets 4 from the horizontal plane is measured with a protractor at the edge of the upper surface of the measuring table, and the measured value obtained is regarded as the angle of repose. EXAMPLES

[0041] 1. Example 1 A model was created using the three-dimensional printer 1 shown in FIG. 1. The soft portion 3a2 used had a diameter of 0.6 cm, a length of 4 cm, and a bending elastic modulus of 300 MPa. The rod 3a was driven so that the base 3a4 of the rod 3a made a circular motion with a diameter of 2.4 cm. The circular motion period was set to 3 seconds. This caused the tip 3a1 of the rod 3a to reciprocate in a direction approaching and away from the raw material supply port 2b1.

[0042] Pellets 4 (styrene-based elastomer, AR-SC-0, manufactured by Aronkasei Co., Ltd., oval shape, major axis length approximately 4.5 mm, minor axis length approximately 2.5 mm, angle of repose 40 degrees, Shore A hardness: 0, MFR at 150°C: 127.52 g / 10 min) were supplied to the hopper 2a of the three-dimensional printer 1 configured as above, and modeling was performed by operating the extruder 2 at 150°C while operating the pushing mechanism 3. As modeling progressed, the pellets 4 were pushed into the cylinder 2b, and a modeled object of the desired shape was obtained.

[0043] 2. Comparative Example 1 Modeling was performed in the same manner as in Example 1, except that the pushing mechanism 3 was not provided. A bridge phenomenon occurred in the pellets 4, and the pellets 4 were not sufficiently supplied into the cylinder 2b, resulting in defective modeling.

[0044] 3. Comparative Example 2 Modeling was performed in the same manner as in Example 1, except that a cylinder mechanism that reciprocates in the up and down direction was used instead of the pushing mechanism 3. Although the bridge of the pellets 4 was broken by the cylinder mechanism, the pellets 4 were not sufficiently supplied into the cylinder 2b, and a modeling failure occurred. [Explanation of symbols]

[0045] 1: Thermal fusion 3D printer 2: Extruder 2a:Hopper 2a1: Placement surface 2b: Cylinder 2b1: Raw material supply port 2c: Nozzle 2d: Screw 2e: Motor 3: Push mechanism 3a: Rod 3a1: Tip 3a2: Soft part 3a3: Hard part 3a4 : Root 3b: Drive mechanism 3b1: Motor 3b2: Motor shaft 3b3:Disc 3b4: Bracket 4: Pellets 4a: Molten resin 5: Strand

Claims

1. A thermal fusion type three-dimensional printer, The apparatus includes an extruder and a pushing mechanism. The extruder includes a hopper, a cylinder, and a nozzle. The hopper is configured to be able to supply pellets into the cylinder through a raw material supply port provided in the cylinder, the extruder is configured to melt and knead the pellets supplied into the cylinder to form a molten resin in the cylinder, and extrude the molten resin through the nozzle to form a strand; The pushing mechanism is configured to push pellets placed on a placement surface of the hopper into the cylinder through the raw material supply port, The pushing mechanism includes a rod that contacts the pellet and a driving mechanism that drives the rod, The rod is driven so that a tip of the rod presses the pellets toward the raw material supply port, The pushing mechanism is configured to convert the vertical movement of the base of the rod into a movement of the tip of the rod approaching or moving away from the raw material supply port, A three-dimensional printer, wherein the movement of the tip of the rod approaching and moving away from the raw material supply port is a movement in a direction different from the up-down direction.

2. A thermal fusion type three-dimensional printer, The apparatus includes an extruder and a pushing mechanism. The extruder includes a hopper, a cylinder, and a nozzle. The hopper is configured to be able to supply pellets into the cylinder through a raw material supply port provided in the cylinder, the extruder is configured to melt and knead the pellets supplied into the cylinder to form a molten resin in the cylinder, and extrude the molten resin through the nozzle to form a strand; The pushing mechanism is configured to push pellets placed on a placement surface of the hopper into the cylinder through the raw material supply port, The pushing mechanism includes a rod that contacts the pellet and a driving mechanism that drives the rod, The rod is driven so that a tip of the rod presses the pellets toward the raw material supply port, The rod comprises a soft portion, The three-dimensional printer, wherein the rod is driven so that the tip of the rod moves toward the raw material supply port while the rod is bent at the soft portion.

3. A thermal fusion type three-dimensional printer, The apparatus includes an extruder and a pushing mechanism. The extruder includes a hopper, a cylinder, and a nozzle. The hopper is configured to be able to supply pellets into the cylinder through a raw material supply port provided in the cylinder, the extruder is configured to melt and knead the pellets supplied into the cylinder to form a molten resin in the cylinder, and extrude the molten resin through the nozzle to form a strand; The pushing mechanism is configured to push pellets placed on a placement surface of the hopper into the cylinder through the raw material supply port, The pushing mechanism includes a rod that contacts the pellet and a driving mechanism that drives the rod, The rod is driven so that a tip of the rod presses the pellets toward the raw material supply port, The three-dimensional printer, wherein the drive mechanism is configured to rotate the base of the rod about a rotation axis extending in a non-vertical direction.

4. The three-dimensional printer according to claim 1 or 3, The rod comprises a soft portion, The three-dimensional printer, wherein the rod is driven so that the tip of the rod moves toward the raw material supply port while the rod is bent at the soft portion.

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